This invention relates to an instrument for extracting a pin.
Removal of a fastening pin from a substrate requires that the pin is gripped securely so that a removal force is transmitted reliably to the pin. Gripping a pin which has an enlarged head can be achieved reliably by engaging the head of the pin. However, when a pin does not have an enlarged head, or when it is necessary to grip the pin other than at the end where it has an enlarged head, gripping the pin requires secure engagement with the side wall of the pin.
This problem is encountered in orthopaedic surgery procedures, for example when a pin is used to mark a location on a bone, or to fasten an instrument such as a cutting guide (for example which defines a surface for a cutting step using a saw, or which defines bores for a drilling or reaming step) to a bone. The pin has to be removed from the bone after the steps involving the pin and the instruments which have been fastened to the bone by means of the pin have been completed.
EP-B-2043538 discloses an instrument for extracting a pin from a substrate. The instrument has an aperture at its tip into which the pin is received prior to extraction.
To insert the pin easily through the aperture, the instrument needs to be placed at the correct position and angle by the surgeon. However, when doing this, the instrument blocks the surgeon's view of the pin and the aperture. As such, the surgeon performs this operation ‘blind’. This can make it very difficult for the surgeon to get the instrument at the right position and angle to ensure that the pin is received through the aperture correctly and may require several attempts.